U.S. patent application number 11/768703 was filed with the patent office on 2008-01-03 for process and apparatus for improving neuronal performance.
This patent application is currently assigned to Research Foundation of the City University of New York. Invention is credited to Zaghloul Ahmed, Andrzej Wieraszko.
Application Number | 20080004484 11/768703 |
Document ID | / |
Family ID | 38877562 |
Filed Date | 2008-01-03 |
United States Patent
Application |
20080004484 |
Kind Code |
A1 |
Wieraszko; Andrzej ; et
al. |
January 3, 2008 |
PROCESS AND APPARATUS FOR IMPROVING NEURONAL PERFORMANCE
Abstract
A method for improving neuronal performance of a target nerve of
a patient according to one exemplary embodiment includes the step
of: exposing the nerve to a pulsed magnetic field generated by DC
current having a predetermined magnetic field strength at a
predetermined frequency. The predetermined magnetic field strength
and the predetermined frequency are selected such that an amplitude
of a compound action potential of the target nerve increases as a
result of the exposure and remains elevated for a time period after
the exposure has ended.
Inventors: |
Wieraszko; Andrzej;
(Princeton, NJ) ; Ahmed; Zaghloul; (Staten Island,
NY) |
Correspondence
Address: |
DARBY & DARBY P.C.
P.O. BOX 770
Church Street Station
New York
NY
10008-0770
US
|
Assignee: |
Research Foundation of the City
University of New York
New York
NY
|
Family ID: |
38877562 |
Appl. No.: |
11/768703 |
Filed: |
June 26, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60817935 |
Jun 30, 2006 |
|
|
|
Current U.S.
Class: |
600/9 |
Current CPC
Class: |
A61N 2/02 20130101 |
Class at
Publication: |
600/009 |
International
Class: |
A61N 2/04 20060101
A61N002/04 |
Claims
1. A method for improving neuronal performance of a target nerve of
a patient, comprising the step of: exposing the nerve to a pulsed
magnetic field generated by DC current having a predetermined
magnetic field strength at a predetermined frequency; wherein the
predetermined magnetic field strength and the predetermined
frequency are selected such that an amplitude of a compound action
potential of the target nerve increases as a result of the exposure
and remains elevated for a time period after the exposure has
ended.
2. The method of claim 1, wherein the amplitude of the compound
action potential is increased by at least about 25%.
3. The method of claim 1, wherein the amplitude of the compound
action potential is increased by at least about 50%.
4. The method of claim 1, wherein the amplitude of the compound
action potential is increased by at least about 100%.
5. The method of claim 1, wherein the step of exposing the nerve
comprises the step of: supplying the DC current from a portable DC
power source in the form of a battery.
6. The method of claim 1, wherein the step of exposing the nerve
comprises the step of: supplying AC current form an AC power
source; and converting the AC current to the DC current using an
AC/DC converter.
7. The method of claim 1, wherein the magnetic field strength is
less than 25 mT.
8. The method of claim 1, wherein the magnetic field strength is
between 10 mT and 25 mT.
9. The method of claim 1, wherein the predetermined frequency is
less than 1.0 Hz.
10. The method of claim 1, wherein the predetermined frequency is
between 0.16 Hz and 0.5 Hz.
11. The method of claim 1, wherein the predetermined frequency is
about 0.16 Hz.
12. The method of claim 1, wherein the time period is greater than
a time period that the nerve is exposed to the pulsed magnetic
field.
13. The method of claim 1, wherein the time period is greater than
1 hour.
14. The method of claim 1, wherein the time period is greater than
6 hours.
15. A method for treating a medical condition in which the neuronal
performance of a patient is impaired, comprising the step of:
improving the propagation of a compound action potential along an
axon of the patient's nervous system by exposing a target nerve to
a pulsed magnetic field generated by DC current.
16. The method of claim 15, further including the step of:
controlling the magnetic field such that a strength of the magnetic
field surrounding the target nerve is between about 15 mT and 25 mT
at a frequency of between about 0.16 Hz and 0.5 Hz resulting in an
amplitude of the compound action potential of the target nerve
increasing as a result of the exposure and remaining elevated for a
first time period after the pulsed magnetic field is stopped, the
first time period being greater than a time period that the nerve
is exposed to the pulsed magnetic field.
17. The method of claim 15, wherein the medical condition is a
pathological condition associated with one of the peripheral
nervous system of the patient and the central nervous system of the
patient.
18. The method of claim 15, wherein the medical condition is a
pathological condition selected from the group consisting
essentially of: neuropathies, joint pathologies, hypo- and
areflexia, a chronic Bell's palsy, and channelopathies.
19. The method of claim 15, wherein the step of improving the
propagation of a compound action potential along an axon of the
patient's nervous system is part of one of a nerve regeneration
treatment and a treatment for selective stimulation of an internal
organ.
20. The method of claim 15, wherein the axons are part of the
spinal cord of the patient.
21. An apparatus for improving neuronal performance of a target
nerve of a patient, comprising: a body for placement proximate to
the target nerve, the body having at least one magnetic field
generation element that receives DC current and generates a pulsed
magnetic field having a predetermined magnetic field strength at a
predetermined frequency, wherein the predetermined magnetic field
strength and the predetermined frequency are selected such that an
amplitude of a compound action potential of the target nerve
increases as a result of exposure to the pulsed magnetic field and
remains elevated for a time period after the exposure has
ended.
22. The apparatus of claim 21, wherein the at least one magnetic
field generating element is a coiled wire.
23. The apparatus of claim 22, wherein the coiled wire is
constructed so that it can completely surround the target nerve in
one plane.
24. The apparatus of claim 22, wherein the at least one magnetic
field generating element comprises a pair of magnetic field
generating elements spaced apart from one another to permit the
target nerve to be positioned between the pair of magnetic field
generating elements.
25. The apparatus of claim 22, further comprising a battery pack
that serves as a power source for providing the DC current.
26. The apparatus of claim 22, further comprising a converter for
converting AC current into the DC current that is received by the
at least one magnetic field generating element.
27. The apparatus of claim 22, further comprising a control unit
for controlling the predetermined magnetic field strength and the
predetermined frequency.
28. The apparatus of claim 27, wherein the control unit is a
programmable unit that includes a user interface that includes a
number of buttons for selecting different modes of operation,
wherein one mode operates at one magnetic field strength and
frequency and another mode operates at another magnetic field
strength and frequency.
29. The apparatus of claim 28, wherein the user interface is
configured to permit the user to enter a location of the target
nerve and a treatment time period which represents a time frame
when the magnetic field is generated with DC current.
30. The apparatus of claim 29, wherein the user interface includes
a touchscreen display and a plurality of icons representing target
treatment locations of the patient's body are displayed, wherein
the control unit is configured such that based on the selected
target treatment location, the control unit calculated a strength
of the applied pulsed magnetic field, an operating frequency and
the time period.
31. The apparatus of claim 22, wherein the body is annular shaped,
with the target nerve being received in an opening defined thereby,
or the body is an elongated flexible band that includes a pair of
magnetic field generating elements spaced apart from one another
along one surface of the band.
32. The apparatus of claim 31, wherein each of the magnetic field
elements has a first fastening element and the one surface of the
band has a complementary second fastening element that permit the
magnetic field element to be securely attached to the one surface
yet repositionable along the one surface such that a distance
between the magnetic field elements is variable.
33. The apparatus of claim 22, wherein the magnetic field strength
is between 10 mT and 25 mT.
34. The apparatus of claim 22, wherein the predetermined frequency
is between 0.16 Hz and 0.5 Hz.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims the benefit of U.S. patent
application Ser. No. 60/817,935, filed Jun. 30, 2006, which is
hereby incorporated by reference in its entirety.
TECHNICAL FIELD
[0002] The present invention relates to pulsed magnetic fields, the
nervous system, and to improvements in neuronal performance. More
specifically, the invention is directed towards a method and an
apparatus for improving neuronal performance by exposure to a
pulsed magnetic field (PMF).
BACKGROUND
[0003] The nervous system is an integral part of the human body and
its major function is to react to the external environment and to
coordinate the function of the different parts of the body
accordingly. The whole nervous system is divided into peripheral
and central nervous systems. Although their physiological role is
similar, there are significant differences in their functions.
Nerves are responsible for transmitting electrical signals
throughout the body to stimulate muscles and regulate the activity
of vital organs. The central nervous system, which consists mainly
of the brain and spinal cord, is responsible for creating
electrical signals which are then sent throughout the body to
initiate a response in an innervated organ or limb. The major
function of the peripheral nervous system is to stimulate and
initiate the contraction of the muscles which move different parts
of the human body (mainly arms and legs), and regulate the activity
of the internal organs. The nerves of the peripheral nervous system
originate in the spinal cord and through long processes called
axons innervate distant body parts. The message travels along the
axon in the form of an electrical signal, called compound action
potential (CAP). Thus, the peripheral nervous system consists of
the different nerves through which the electrical signals travel
throughout the body and electrical signals are transmitted from one
nerve to another through axons, fiber-like extensions from a nerve
cell.
[0004] An electrical signal traveling through a nerve is called an
action potential. This potential is quantifiable and can be
expressed in terms of voltage. This potential is responsible for
initiating a response in an organ or limb. The strength of the
compound action potential (the sum of the action potentials
generate by several axons) correlates to the strength of the
response. For example, if the compound action potential is sent
through a peripheral nerve to initiate the contraction of a muscle,
the stronger the compound action potential, the faster and/or
stronger the muscle contraction will be.
[0005] Any impairment or inhibition in the transmission of the
compound action potential can result in a weaker response from the
innervated organ. Impairment of the compound action potential
transmission could even result in paralysis of the skeletal
muscles, i.e., the impairment causes the compound action potential
to be too weak to initiate any response in the skeletal muscles,
and thus, the patient is unable to move the limb, etc. There are
various diseases and conditions in which the transmission of the
compound action potential is impaired. Neuropathies such as distal
axonopathies, myelinopathies, neuronopathies and autonomic
neuropathies are all characterized by a significant reduction in
the ability of the nerves to generate and transmit an action
potential. Hyporeflexia and areflexia, characterized by weak or
absent reflexes, are often linked to diminished compound action
potential transmission. The symptoms of these diseases and
conditions may be alleviated and the functioning of the innervated
organs can be improved with a treatment that facilitates the
transmission of the compound action potential.
[0006] As mentioned above, the role of the spinal cord, which is a
part of the central nervous system, is to transmit the information
between the brain and the peripheral nervous system. Any damage to
the spinal cord may have devastating effects on the performance of
the vital body function. The brain, besides controlling the
activity of the spinal cord and peripheral nervous system, is
responsible for learning and memory and for utilizing acquired
information to improve survival skills.
[0007] Even a person without such a disease or condition could
benefit from a treatment that facilitates compound action potential
transmission. Such a treatment could enhance the performance of an
innervated organ, enhancing the person's performance of an activity
that utilizes the innervate organ. Furthermore, the treatment may
be used to alleviate pain associated with a muscle, or to simply
provide a person with a healthier feeling in that muscle.
[0008] Magnetic fields have been used in treatments for reducing
pain, facilitation of bone healing and to promote overall muscle
activity. The effect of a steady magnetic field on the compound
action potential of sensory nerves have been described in McLean et
al. "Effects of steady magnetic fields on action potentials of
sensory neurons in vitro", available at
http://www.holcombhealthcare.com/reports/pub-effect.html, which is
hereby incorporated by reference. The effects of a steady magnetic
field on neuronal performance are not significant, and they are not
sustained once the magnetic field is removed. Furthermore, there is
some evidence that suggests that the body adapts to the steady
magnetic field after a certain amount of time, and therefore
exposure to that field will have no affect on neuronal
performance.
[0009] Pulsed magnetic fields (PMF), i.e., magnetic fields in which
the field strength is regularly alternated between different field
strengths, have also been used in various treatments. Laycock, et
al. "Pulsed magnetic field therapy and the physiotherapist",
available at http://www.tgselectronics.com.au/physio.html, which is
hereby incorporated by reference, discusses using a PMF to resolve
soft tissue injuries, facilitate bone fractures and reduce pain.
Laycock describes that a "magnetic field pulsed at 5 Hz with a base
frequency of 50 Hz" was as useful as an icepack in dispersing
bruises and that a magnetic field having "a base frequency of 200
Hz pulsed at between 5 and 25 pulses per second" was most effective
in reducing pain. The PMF used in such treatments is the result of
using a magnetic field generating element with an AC power source.
As the AC current alternates between its maximum positive and
negative flows, the magnetic field pulsates between its maximum
field strengths in both polarities, creating a saw-tooth like
shaped magnetic field wave form, such as that shown in FIG. 1a. The
magnetic field described in Laycock is one in which the saw-tooth
like base magnetic field is alternately turned on and off at a
given frequency, such as that shown in FIG. 1b. These treatments,
however, do not produce significant improvements in neuronal
performance.
[0010] It would therefore be desirable and advantageous to provide
method and an apparatus of improving neuronal performance by
facilitating the transmission of the compound action potential by
exposure to a magnetic field that overcomes the disadvantages of
the prior art, while at the same time improves neuronal
performance.
SUMMARY
[0011] A method for improving neuronal performance of a target
nerve of a patient according to one exemplary embodiment includes
the step of: exposing the nerve to a pulsed magnetic field
generated by DC current having a predetermined magnetic field
strength at a predetermined frequency. The predetermined magnetic
field strength and the predetermined frequency are selected such
that an amplitude of a compound action potential of the target
nerve increases as a result of the exposure and remains elevated
for a time period after the exposure has ended.
[0012] An apparatus for improving neuronal performance of a target
nerve of a patient, according to one exemplary embodiment includes
a body for placement proximate to the target nerve, with the body
having at least one magnetic field generation element that receives
DC current and generates a pulsed magnetic field having a
predetermined magnetic field strength at a predetermined frequency.
The predetermined magnetic field strength and the predetermined
frequency are selected such that an amplitude of the compound
action potential of the target nerve increases as a result of
exposure to the pulsed magnetic field and remains elevated for a
time period after the exposure has ended.
[0013] The method and apparatus of the present invention are useful
in a treatment to enhance neuronal performance. The present
treatment is useful for people suffering from a disease or
condition in which the transmission of the compound action
potential is impaired. Examples of such diseases and conditions are
neuropathies, such as, distal axonopathies, myelinopathies,
neuronopathies and autonomic neuropathies and hyporeflexia and
areflexia. This treatment is even useful in the regeneration of
muscles or organs that have been considered paralyzed due to severe
impairment of the compound action potential transmission. The
present treatment is also useful in enhancing the neuronal
performance of an animal not suffering from any such disease or
condition. Such a person could enhance the performance of a
particular organ or muscle by enhancing the neuronal performance of
that organ or limb. This treatment is also useful in relieving pain
or to simply provide a person with a healthier feeling in a
particular muscle or organ.
BRIEF DESCRIPTION OF THE FIGURES
[0014] These and other objects and features of the invention will
become more apparent by referring to the drawings, in which:
[0015] FIG. 1a is a schematic illustrating a wave form of a
conventional pulsed magnetic field (PMF);
[0016] FIG. 1b is a schematic illustrating a wave form of a
conventional PMF with a base frequency;
[0017] FIG. 2 is a schematic illustrated a wave form of a PMF
according to one embodiment of the present invention;
[0018] FIG. 3 is a schematic block diagram illustrating one
exemplary method according to the present invention for improving
neuronal performance;
[0019] FIG. 4 is schematic block diagram illustrating one exemplary
apparatus according to the present invention for improving neuronal
performance;
[0020] FIG. 5a is an end view of a ring-shaped apparatus according
to one exemplary embodiment of the present invention and for
insertion of a target body therein;
[0021] FIG. 5b is a side elevation view of a flexible band
according to one exemplary embodiment and for placement against a
target body;
[0022] FIG. 6a is a depicts a graph showing the amplitude of the
compound action potential vs. time of the nerve of Example 1;
[0023] FIG. 6b is a graph showing the amplitude of the compound
action potential vs. the potential of the electrical stimulus for
the nerve of Example 1 before and after exposure to the steady
PMF;
[0024] FIG. 7a is a graph showing the amplitude of the compound
action potential vs. time for the control nerve of Example 2;
[0025] FIG. 7b is a graph showing the amplitude of the compound
action potential vs. time of the nerve of Example 2;
[0026] FIG. 8 is a graph showing the amplitude of the compound
action potential vs. time for the spinal cord segment of Example
3;
[0027] FIG. 9 is a diagram showing an experimental arrangement to
record compound antidromic potentials from hippocampal slices;
and
[0028] FIG. 10 is a graph showing the effect of PMF on the
antidromically-evoked potential recorded from a specimen of Example
4.
DETAILED DESCRIPTION OF THE INVENTION
[0029] According to one aspect of the present invention, neuronal
performance can be improved by exposing target neurons to a pulsed
magnetic field (PMF) generated by DC current. This is in contrast
to conventional PMF type devices and applications where the pulsed
magnetic field is generated by AC current. This causes the magnetic
field strength to constantly change, alternating between maximum
values in both polarities. FIG. 1a illustrates a wave form 10 of a
conventional pulsed magnetic field (PMF). The wave form 10 shows
that the magnetic field strength is constantly changing,
alternating between maximum points 12 in the positive polarity
(maximum positive values) and maximum points 14 in the negative
polarity (maximum negative values).
[0030] A PMF with a base frequency, as described by the previously
mentioned Laycock reference, is in the form of a PMF that is
alternately turned on and off so as to produce the wave form 20
illustrated in FIG. 1b. Segments 22 of the wave form 20 show that
when the PMF is activated, the magnetic field strength alternates
between maximum values in both polarities similar to FIG. 1a.
Segment 24 of the wave form shows that when the PMF is not
activated, the magnetic field strength remains zero.
[0031] Accordingly, in either of the PMF arrangements of FIGS. 1a
and 1b, the magnetic strength alternates between maximum values in
both polarities.
[0032] Unlike conventional PMF devices and applications, such as
those in FIGS. 1a and 1b, a method of treatment and related
apparatuses (medical or therapeutic instruments) according to the
present invention is based on a PMF that is generated by DC
current. Unlike AC current, in which the current is constantly
moving between a maximum positive and maximum negative flows, DC
current maintains a constant current flow. This allows for a PMF in
which the magnetic field strength alternates between a constant
maximum strength in a single polarity and zero when the magnetic
field is off. The magnetic field is maintained at a predetermined
maximum field strength for a predetermined amount of time, and is
then maintained at zero for a predetermined amount of time. In
other words, the magnetic field is maintain "on" for a first period
of time and is then maintained "off" for a second period of time
which can be the same or different from the first period of
time.
[0033] FIG. 2 shows an exemplary magnetic field wave form 30 of a
PMF generated by DC current according to the present invention. The
wave form 30 includes four separate phases, namely, a) a rising
phase 32, b) a steady maximum phase 34, c) a falling phase 36, and
d) a steady zero phase 38. For example and according to one
embodiment, a PMF according to the present invention can alternate
between a maximum magnetic field strength of about 15 mT and about
0 mT at a frequency of about 0.16 Hz; however, the field strength
and frequency can be other values as described below.
[0034] Methods for establishing a PMF are well known in the art,
and according to the present invention, any number of conventional
methods can be used to generate the desired PMF wave form so long
as it based on DC current. One example of such a method utilizes a
coiled wire. When a current is applied to the coil, a magnetic
field is created around the coil. When the current is removed from
the coil, the magnetic field ceases to exist. Therefore, by
alternately applying a current to and removing a current from a
coiled wire at a predetermined frequency, a PMF is created.
[0035] As described above, a PMF is typically generated as a result
of AC current flowing through a magnetic field generating element,
such as a coiled wire, to generate the wave form illustrated in
FIG. 1a. Since the PMF according to the present invention is
generated by DC current, if the power supply being used is an AC
power supply, a converter can be utilized to convert the AC current
to DC current before it flows through the magnetic field generating
element (coiled wire).
[0036] As previously mentioned, the present invention is directed
towards a method of improving neuronal performance by exposing a
target nerve of a patient to a PMF generated by a DC current. The
nerve can be associated with the central nervous system or
associated with the peripheral nervous system. Preferably, the
nerve is associated with the peripheral nervous system. It has been
observed that when the target nerve is exposed to a PMF generated
from a DC current having a predetermined frequency at a
predetermined magnetic field strength, the transmission of the
compound action potential through that target nerve is
advantageously improved. This result in an increase of the
amplitude of the action potential for a given stimulant when
compared to the action potential for that stimulant in the nerve
prior to the exposure to the PMF. As is known, if the amplitude of
the compound action potential does not cross a threshold, the nerve
does not function in a normal manner and the motor skills of the
patient can be diminished or completely lost in a given area since,
for example, muscle contraction in the given area may be lost.
[0037] The amplitude of the compound action potential gradually
increases as the nerve is exposed to a PMF generated by DC current
according to the present invention. Furthermore, the increase in
the amplitude of the compound action potential is sustained over a
period of time after exposure to the PMF and after removal of the
PMF. The length of the period of time where improved neuronal
performance is realized depends on a number of different
parameters, such as characteristics of the PMF and the length of
exposure of the target nerve to the PMF.
[0038] It will be appreciated that different PMFs generated by DC
current improve the performance of neurons to different degrees
depending on a number of different parameters including the type of
target nerve, its location, etc. More particularly, optimization of
the neuronal performance enhancement depends on the parameters of
the PMF, such as the field strength and frequency. Additionally,
the length of time in which the nerve is exposed to PMF will affect
the enhancement of neuronal performance. The present inventors have
discovered a set of parameters for the PMFs that are capable of
enhancing neuronal performance. The enhancement can easily be
measured by the increase of the amplitude of the compound action
potential for a given stimulant when the nerve is exposed to a PMF
when compared to the performance of nerve prior to the PMF
exposure. The measurements of the amplitude of the compound action
potential can be made after the nerve has been exposed to a PMF for
a predetermined amount of time.
[0039] The PMF of the present invention has a predetermined
frequency and a predetermined field strength so that the after a
predetermined amount of time of exposure to the PMF, the amplitude
of the compound action potential is increased a predetermined
amount. The increase in amplitude of the compound action potential
is preferably by at least 10% compared to the amplitude of the
compound action potential before application of the PMF of the
present invention. Preferably the amplitude of the compound action
potential is increased by at least 25%. More preferably, the
amplitude of the compound action potential is increased by at least
50%. Even more preferably, the amplitude of the compound action
potential is increased by at least 100%. The field strength is
typically measured at the location of the nerve.
[0040] The PMF of the present invention has a predetermined
frequency so that exposure to the PMF causes the amplitude of the
compound action potential to increase. The actual frequency that
will achieve the best results varies with the particular target
nerve and the magnetic field strength. In one embodiment of the
invention, the frequency of the PMF is less than 0.5 Hz. In another
embodiment, the frequency is between about 1 Hz and about 0.05 Hz
or between 0.16 Hz and 0.5 Hz. In addition, the frequency can be
about 1 Hz, about 0.5 Hz, or about 0.16 Hz. In an alternate
embodiment of the invention, the frequency is at least about 0.5
Hz.
[0041] The PMF of the present invention have a predetermined
magnetic field strength so that exposure to the PMF causes the
amplitude of the compound action potential to increase. The actual
magnetic field strength that will achieve the best results varies
with the particular target nerve and the frequency of the PMF. In
one embodiment of the invention, the magnetic field strength of the
PMF is less than about 100 mT, less than about 50 mT, less than
about 25 mT or less than about 15 mT. Preferably, a range of the
magnetic field strength is between about 25 mT and 10 mT. Even more
preferably, the magnetic field strength is from about 15 mT to
about 12 mT. Even more preferably, the magnetic field strength is
about 15 mT or about 12 mT.
[0042] FIG. 3 shows a block diagram 100 illustrating one exemplary
method according to the present invention. Block 100 depicts the
step of exposing a target nerve to a PMF generated by DC current
according to the present invention. The DC current can be supplied
by a DC power source 102 or alternatively, the DC current is
supplied by an AC power source 104 which provides AC current that
is converted to DC current in an AC/DC converter 106. The
parameters (characteristics or properties) of the PMF, such as the
associated frequency and magnetic field strength, are controlled so
that the exposure to the PMF causes the target nerve to experience
an increase in the amplitude of its compound action potential.
[0043] Another aspect of the present invention relates to the means
or manner in which the PMF of the present invention is generated
and applied to target nerve. More particularly and according to the
present invention, any number of different apparatuses can be
provided for applying the PMF, with the type of apparatus and its
construction depending, in part, upon where the target nerve is
located and also the location where the treatment will occur.
[0044] FIG. 4 is a schematic diagram of one exemplary apparatus 150
according to the present invention for applying the PMF to a target
nerve 160. The apparatus 150 contains a magnetic field generating
element 152 which receives an electrical current, in this case DC
current. Magnetic field generating elements 152 are well known in
the art, and according to the present invention, any number of
elements can be used. One example of a suitable magnetic field
generating element 152 is a magnetic coil through which an
electrical current (DC current) can flow. Magnetic coils are
typically circular, however, other coiled shapes and configurations
are equally possible. Another example of a magnetic field
generating element 152 is a straight electrical wire, through which
an electrical current (DC current) can flow.
[0045] The magnetic field strength of the apparatus 150 varies as
the amount of current flowing through the magnetic field generating
element 152 varies and as the distance from the target nerve 160 to
the element 152 varies. In general, a greater electrical current
will generate a stronger magnetic field. Additionally, the magnetic
field will be stronger at locations closer to the element 152.
However, there are exceptions to this rule, such as inside a coil
magnet. According to the present invention, the electric field
strength can be adjusted to a predetermined strength which is
effective in enhancing neuronal performance by adjusting the
electrical current and by varying the distance of the nerve 160
from the element 152.
[0046] The electrical current flowing through the magnetic field
generating element 152 must be DC current according to the present
invention in order to achieve the beneficial and advantageous
results described herein. However, the current can be supplied by a
DC power source 154 or an AC power source 156. When the AC power
source 156 is used, a converter 158 is utilized to convert the AC
current to DC current before the current flows through the magnetic
field generating element 152.
[0047] Furthermore, the power source can be portable or
non-portable. Different power sources are well known in the art,
and according to the present invention, a number of power sources
can be used. An example of a portable power source is a battery,
which typically supplies a DC current and therefore can be directly
attached to the magnetic field generating element 152 to supply DC
current thereto. An example of a non-portable power source is an
electrical outlet. In the U.S., electrical outlets provide AC
current and therefore, when using an electrical outlet in the U.S.,
converter 158 is utilized to convert the AC current to DC current.
The apparatus 150 can also include a control unit 162 (controller),
through which the current through the magnetic field generating
element and the PMF frequency can be controlled.
[0048] Preferably, the control unit 162 is of a programmable type
in one embodiment to permit the operator to enter information
relevant for the treatment of the nerve and/or selection of the
operating parameters of the apparatus 150. For example, the
operator, who may be a physician or the patient themselves, can
input the desired magnetic field strength and the frequency. In
addition, a time period for the length of the treatment can be
inputted into the controller and based on this inputted
information, the controller 162 can operate the magnetic field
element 152 in a manner that results in the desired PMF being
generated.
[0049] Preferably, the control unit 162 is in the form of a digital
interface to permit easy entry of information.
[0050] In addition, the user interface can include interactive,
illustrative icon buttons that depict general locations of the
target nerve 160 and also a set of interactive illustrative icon
buttons can be presented that depict the type of apparatus being
used with the controller 162 since it will be appreciated and
understood that the controller 162 can be used with a number of
different apparatuses, such as those illustrated in FIGS. 5a and
5b. Accordingly, the user interface can include icons that depict
various parts of the human body, such as an arm or leg or a torso
to which the apparatus 150 is to be applied and which generally
represents the location of the target nerve. Similarly, the user
interface can include icons that illustrate the different types of
apparatuses for applying the PMF, e.g., a ring-shaped band, an open
ended, flexible band or two separate pads for placement on the body
with the target nerve 160 lying therebetween. The selection of the
type of device can be programmed to provide any slight modification
to the operating conditions so that optimization of the operating
conditions is achieved.
[0051] In one embodiment, the controller will take the inputted
target nerve location information and use it in calculating the
necessary operating parameters of the PMF that will result in the
inputted magnetic field strength at the target nerve itself. For
example, the controller 162 can take into account if the target
nerve 160 is deeper in the body of the patient and therefore, the
distance from the target nerve to the magnetic field generating
element 152 will be greater and this can influence the operating
parameters of the PMF. In addition, the controller can be
configured so that based on the inputted targeted body part that is
selected with the user interface as by selecting one of the icons
(that illustrates various body parts) of the user interface
display, the controller will select the magnetic field strength,
operating frequency and the time period for the treatment. In this
manner, the user simply selects the body location that is to be
treated and the controller then initiates the proper treatment for
the patient based on stored operating parameters.
[0052] A treatment is defined as a length of time in which a nerve
is exposed to a PMF. The present invention allows for various
different treatment arrangements using PMFs of different strengths
and frequencies. For example, according to one embodiment of the
invention, each treatment is performed using a PMF generated by DC
current having the same predetermined magnetic field strength and
frequency. According to another embodiment of the invention, an
initial treatment is performed using a PMF having a first
predetermined field strength and frequency, and the several
subsequent treatments are performed using a PMF having a second
predetermined field strength and frequency. Therefore, one can
perform an initial treatment using a stronger PMF and the following
treatments could use a weaker PMF. It will also be understood that
the control unit 162 can be configured to provide a multi-mode
application in which the operator can select from one of the saved
programs in which a first treatment mode using a PMF having a first
predetermined field strength and frequency is first performed and
then a second treatment mode using a PMF having a second
predetermined field strength and frequency is subsequently
performed. The time periods for each of these treatments is
variable and can be selected by the operator. For example, the
first treatment mode can be programmed to last more than 75% of the
total time, with the second treatment mode simply being an ending
treatment.
[0053] However, the control unit 162 can also be programmed so that
the two treatments are separated by a significant amount of time
and a timer of the control unit 162 can keep track of the time and
then instructed the control unit 162 to send an alert, e.g., a
chime or alarm, to the patient reminding the patient that the
second treatment should be initiated. For example, one treatment
program can call for a second treatment to be applied about 6-8
hours after the initial treatment and this second treatment can be
at a different field strength and frequency than the first
treatment. This second treatment can be thought of as a refresher
treatment or the like and can last for a shorter time period than
the first treatment.
[0054] It will also be appreciated that the above versatility and
options allows for the use of a non-portable apparatus capable of
creating a stronger PMF for the initial treatment, and the use of a
portable apparatus for the subsequent treatments, providing the
patient with great flexibility when designing a treatment
schedule.
[0055] According to the present invention, the target nerve 160 is
exposed to a PMF generated by DC current by placing the apparatus
150 in the vicinity of the target nerve 160 to be treated. The
exact placement of the apparatus 150 will depend on the location of
the nerve 160 to be treated, the overall shape of the apparatus and
the particular magnetic field generating element used in the
apparatus. For example, if the nerve 150 to be treated is in the
arm of the patient, the arm can be placed through a circular
apparatus with a large circular magnetic coil, which is described
below with reference to FIG. 5a. The current through the coil can
then be adjusted to produce a magnetic field with a predetermined
magnetic field strength at the location of the nerve. Thus, the
magnetic field strength that is entered into the programmable
control unit 162 is the strength of the magnetic field that is to
be found at or near the target nerve as opposed to the strength of
the magnetic field at another location, such as the skin surface.
Thus, when the control unit 162 has modes that can be selected to
input the location of the target nerve 160, the control unit 162
can then take this inputted information into consideration when
selecting the appropriate operating conditions that will result in
the strength of the magnetic field being the predetermined, desired
value at or near the target nerve 160 itself which is separated by
a distance from the coiled wire. Thus, the control unit 162 takes
into account this normal, typical distance of separation from the
target nerve 160 and the coiled wire.
[0056] In an alternate embodiment, separate magnetic field
generating elements 152, such as small magnetic coils, could be
placed on opposite sides of the patient's arm, producing a PMF at
the location of the nerve that is a combination of PMFs produced by
each element. The elements could be part of the same apparatus,
i.e., they may share the same power source and controls, or they
may be separate apparatuses, each having their own power source and
controls as described in more detail below.
[0057] In another example, if the nerve 150 to be treated is in an
internal organ, such as the liver, a circular apparatus with a
circular magnetic coil can be placed around the patients body
(torso) so that it is located in substantially the same plane as
the liver. Alternatively, separate magnetic field generating
elements, such as small magnetic coils, could be placed around the
patients abdomen, in substantially the same plane as the liver.
[0058] As previously mentioned, the method and apparatus of the
present invention are useful in a treatment to enhance neuronal
performance. This treatment is useful for people suffering from a
disease or condition in which the transmission of the compound
action potential is impaired. Examples of such diseases and
conditions are neuropathies, such as, distal axonopathies,
myelinopathies, neuronopathies and autonomic neuropathies and
hyporeflexia and areflexia. This treatment is even useful in the
regeneration of muscles or organs that have been considered
paralyzed due to severe impairment of the compound action potential
transmission. This treatment is also useful in enhancing the
neuronal performance of an animal not suffering from any such
disease or condition. Such a person could enhance the performance
of a particular organ or muscle by enhancing the neuronal
performance of that organ or limb. This treatment is also useful in
relieving pain or to simply provide a person with a healthier
feeling in a particular muscle or organ.
[0059] FIG. 5a depicts one embodiment of the apparatus of the
present invention. The apparatus 200 includes a main body 202 which
contains magnetic field generating element 204. The magnetic field
generating element is a coiled wired. Preferably, the main body 202
is made of an insulating material, allowing the patient to touch
the apparatus without risk of electric shock. A patient could place
his or her limb (or even the torso) through the opening 206 of the
main body 202 to perform a treatment on a target nerve located in
that limb (or in the torso). Wires 208 connect the magnetic field
generating element 204 to a control unit 210 and a power supply
212. The control unit 210 may include controls which allow the
patient to adjust the current flowing through the magnetic field
generating element and the frequency of the PMF (the control unit
210 can be similar or identical to control unit 162 and therefore
include the above described features). If the power supply provides
AC current, a converter can be used to convert the AC current to DC
current. For simplicity, a converter is not shown in FIG. 5a. The
apparatus may include a handle 214, by which the patient can hold
the apparatus during treatments.
[0060] Alternatively and instead of a handle 214, the apparatus 200
can include a mounting element, such as a post or bracket, that can
be releasably attached and coupled to a stand or the like in such a
way that the apparatus 200 is supported by the stand but also, can
be moved over a range of motion. For example, the attachment
between the apparatus and the stand can be of a pivotal nature such
that the apparatus 200 can be pivoted relative to the stand and
preferably can be rotated also relative to the stand to permit, the
operator or patient to move the apparatus 200 over a range of
motion to permit the apparatus 200 to be moved to a proper location
where the target nerve lies therebetween. For example, the patient
can lie on a bed or treatment table and then the apparatus 200 can
be manipulated so as to position the limb or torso of the patient
within the body 202.
[0061] It will be appreciated that the apparatus 200 can be
constructed to be of a portable type in that the control unit 210
and the power supply 212 can be incorporated into a portable pack
or the like to which the body 202 is connected via electrical wire
208. In this case, the power supply 212 will be a DC battery that
can be housed in a compartment that is part of a control module
that includes the control unit 212 and some type of display to
display information, such as the values of the magnetic filed, the
frequency, etc., and preferably, the control module will have a
user interface, such as a keypad that permits entry of the
information.
[0062] FIG. 5b depicts a second embodiment of an apparatus 250 of
the invention. The apparatus 250 includes magnetic field units 256
which are attached to main body 252. The magnetic field units 256
each contains a magnetic field generating element 254 (only one is
illustrated in FIG. 5(b)). The magnetic field generating elements
254 are preferably coiled wires. Preferably, the magnetic field
units 256 and the main body 252 are made of an insulating material,
allowing the patient to touch the apparatus 250 without risk of
electric shock.
[0063] The body 252 can be in the form of a flexible body that can
readily bend in areas, especially the areas surrounding the units
256 and in the illustrated embodiment, the body 252 is in the form
of an elongated flexible band that can be made of synthetic
material, etc., that can readily be bent so as to shape the body
252 to the shape of the patient's body and in particular, to the
target area of the patient, such as a limb or torso. A patient can
thus wrap the main body 252 around a limb on his or her body or
around his or her torso, to perform a treatment on a nerve in that
limb or torso.
[0064] This would allow for each magnetic field generating unit 254
to be placed in separate locations in the vicinity of the nerve.
One or more wires 258 connect both magnetic field generating
elements 254 to a control unit 260 and a power supply 262.
[0065] The control unit 260 can include controls which allow the
patient to adjust the current flowing through the magnetic field
generating element and the frequency of the PMF and can function
and have the features previously described with reference to
control unit 162. If the power supply 262 provides AC current, a
converter can be used to convert the AC current to DC current. For
simplicity, a converter is not shown in FIG. 5b.
[0066] The apparatus 250 preferably includes some type of means for
holding and maintaining the body 252 on the patient. For example,
the body 252 can include a strip of hook and loop type material
264, which the patient can adhere to a part of the main body 252,
holding the apparatus 250 in place during treatments.
[0067] In yet another aspect of the present invention and according
to another embodiment of the present invention, each of the units
256 includes a releasable fastening means, such as a hook and loop
fastener, that mates with a complementary fastener that is part of
the body 252 to permit the units 256 to be securely fastened to the
body 252 yet readily repositioned thereon to permit difference not
only different orientations of the units 256 but also different
positions between the units 256. Thus, in the case of a hook and
loop type fastening system, one of the fastening elements (e.g.,
pads or strips of hook and loop type material) is associated and
coupled to the unit 256 and the other of the fastening elements
(e.g., pads or strips of hook and loop type material) is associated
and coupled to one face/surface of the body 252. For example, the
entire front surface of the body 252 that faces the patient in use
can have a layer of hook and loop type material and this permits
the units 256 with their hook and loop type material facing this
layer to be able to be readily attached and repositioned along the
front surface. This permits strategic placement of the units 256 so
as to better position the target nerve between the two units 256.
For example, a larger sized patient may require a greater distance
of spacing between the two units 256 then a smaller patient. This
embodiments permits such customization.
EXAMPLE 1
[0068] A segment of a mouse somatic nerve (sciatic nerve) was
isolated. The nerve was placed in a chamber surrounded by a coiled
wire. The coiled wire was connected to an electrical outlet
supplying AC current, which was converted by a converter to DC
current. The flow of current through the coil was regulated by a
computerized timer.
[0069] In order to mimic in vivo conditions, the nerve was
electrically stimulated every 30 seconds to evoke a compound action
potential. The electrical stimulations continued throughout the
experiment, i.e., before the PMF was activated, while the PMF was
activated and after the PMF was deactivated. The amplitude of the
compound action potential was measured and recorded by the computer
throughout the experiment. After a short period of time, the
response of the nerve stabilized, i.e., the compound action
potential of the nerve remained about the same for each subsequent
electrical stimulation. At this point the PMF was activated for
about 30 minutes. The magnetic field strength at the location of
the nerve was about 15 mT and the frequency of the PMF was set to
0.16 Hz. The PMF was then deactivated, and for the remainder of the
experiment, the nerve was electrically stimulated and the compound
action potential was recorded without the PMF.
[0070] FIG. 6a shows a graph 300 depicting the results of this
experiment. Y-axis 302 depicts the amplitude of the compound action
potential in milivolts and x-axis 304 depicts time in minutes. Line
306 shows the compound action potential of the nerve as it was
measured throughout the experiment. At point 308 the PMF was
activated. At point 310 the PMF was deactivated. It is evident from
the segment of line 306 between points 308 and 310 that the
exposure to the PMF increased the compound action potential of the
nerve. It is evident from the segment of line 306 after point 310
that the increased compound action potential was sustained even
after the PMF was deactivated.
[0071] FIG. 6b shows a graph 350 depicting the amplitude of the
compound action potential of the nerve for different stimuli before
and after the nerve is exposed to the PMF. Y-axis 352 depicts the
amplitude of the compound action potential in milivolts and x-axis
354 depicts the voltage of the stimulus in volts. Line 354 shows
the amplitude of the compound action potential for different
stimuli before exposure to the PMF. Line 354 shows the amplitude of
the compound action potential after the exposure to the PMF. It is
evident that threshold of the electrical stimulus, i.e., the
minimum strength of the stimulus to induce a compound action
potential with a particular amplitude, was significantly
reduced.
EXAMPLE 2
[0072] A further experiment was performed using the same method and
apparatus of Example 1. In this experiment, lidocaine was
administered to the nerve after the nerve's response to the
electrical stimulation stabilized. Lidocaine has a suppressive
effect on the compound action potential, and the amplitude of the
compound action potential of the nerve decreased significantly.
FIG. 7a shows a graph 400 which depicts the results of a control
study, showing the effect of lidocaine on the compound action
potential. Y-axis 402 depicts the amplitude of the compound action
potential in milivolts and x-axis 404 depicts time in minutes. Line
406 depicts the compound action potential of the nerve. 150 uM of
lidocaine is administered to the nerve at point 408. The segment of
line 406 before point 408 depicts the compound action potential of
the nerve prior to the administration of lidocaine. The segment of
line 406 after point 408 depicts the compound action potential of
the nerve after the administration of lidocaine. It is evident that
the amplitude of the compound action potential decreases
significantly as a result of the administration of lidocaine. This
mimics a nerve suffering from a disease or condition that impairs
the transmission of the compound action potential. The PMF was then
activated, and the experiment was performed as described in Example
1. Due to the exposure to the PMF, the amplitude of the compound
action potential increased to amplitudes greater than the
pre-lidocaine, pre-PMF exposure level.
[0073] FIG. 7b shows graph 450 depicting the results of this
experiment. Y-axis 452 depicts the amplitude of the compound action
potential in milivolts and x-axis 454 depicts time in minutes. Line
456 shows the amplitude of the compound action potential throughout
the experiment. At point 458, lidocaine was administered to the
nerve. At point 460 the PMF was activated, and at point 462, the
PMF was deactivated. It is evident from the segment of line 456
between point 458 and 460 that the lidocaine decreased the compound
action potential. It is evident from the segment of line 456
between points 460 and 462 that exposure to the PMF increased the
compound action potential to amplitudes even greater that before
the lidocaine was administered. And it is evident from the segment
of line 456 after point 462 that the increase in the amplitude of
the compound action potential was sustained after the PMF was
deactivated. This demonstrates that through exposure to a PMF
generated by DC current, it is possible to enhance the performance
of a nerve suffering from a disease or condition that impairs the
transmission of the compound action potential.
EXAMPLE 3
[0074] The influence of the PMF, according to the present
invention, on the compound action potential recorded from a spinal
cord sample is illustrated in the graph of FIG. 8. In particular,
segments of the spinal cord were prepared as described in the
Agrawal and Fehlings reference incorporated above. Following
decapitation and laminectomy, a thoracic segment of the spinal cord
(20-30 mm) was removed and placed in cold Ringer's solution.
Subsequently, the dorsal column was cut longitudinally (to form a
hemisection) and this sample was placed in the recording chamber.
The stimulating and recording electrodes were located on both ends
of the preparation. Following a preincubation period, the cut
samples were individually transferred to the recording chamber and
the compound action potential (CAP) was followed for several
minutes to achieve a stable recording. Then, the preparation was
exposed to a PMF for a time period of 30 minutes at a frequency of
about 0.16 Hz.
[0075] FIG. 8 depicts the results of this testing procedure and in
particular, the graph shows the influence of the PMF on the
compound action potential recorded from a spinal cord sample. "PMF
On" and "PMF Off" indicate the beginning and end of the exposure of
the 0.16 Hz PMF. As shown, the amplitude of the compound action
potential from the spinal cord was elevated by 232%.+-.19%.
EXAMPLE 4
[0076] FIG. 9 shows the effect of PMF on antidromically evoked
compound action potential (CAP) recorded from hippocampal slices
taken from a brain. The hippocampal slices were prepared according
to the standard procedure disclosed in the Wieraszko reference
previously incorporated. The arrangement of the antidromically
stimulating electrode and the electrode recording antidromic
compound action potential (CAP) is depicted in the graph of FIG. 9.
The influence of PMF on antidromically evoked potentials is shown
in FIG. 10. The hippocampal slices were incubated in a calcium free
medium and with 2 mM kynurenic acid. Addition of kynurenic acid
(blocker of glutamergic receptors) to the slice containing chamber
and the omission of calcium eliminate any contribution of
glutamergic synaptic transmission to the generation of the recorded
potentials. The graph of FIG. 10 shows the amplitude of the
population spikes during the entire trial run. The results show
that the PMF has increased significantly the size of the population
spike and in particular, the amplitude of the CAP increased
significantly, e.g., 183%.+-.11%.
[0077] The present invention has widespread applicability since the
present invention provides an apparatus and method of pulsed
magnetic field to treat pathologies of the peripheral nerve system.
Since the present invention dramatically improves the propagation
of the compound action potential along the axon, the present
invention can be applied in pathological conditions, expressed as
an impairment of this propagation. Therefore, the PMF methods of
the present invention can be used to treat the following
pathological conditions:
[0078] 1. Neuropathies: conditions generally classified as
symmetric generalized neuropathies (polyneuropathies), which are
further classified into: distal axonopathies (in case of diabetes),
myelinopathies, neuronopathies (amyotrophic laterial sclerosis,
known as ALS and hereditary dysautonomia). All of these
neuropathies are characterized by significant reduction in the
ability of the nerves to generate and to conduct a compound action
potential.
[0079] 2. Joint pathologies: denervation of joints in some diseases
(Charcot's neuropathy) leads to severe osteoarthritic changes in
the affected joints. This indicated that proper innervation of the
joint is vital for its function. Even a subtle reduction in nerve
conductions or changes in innervations can cause osteoartheritic
changes in the affected joints. Increasing the excitability of the
nerves around the joint can exert a trophic effect improving its
viability. It may also enhance the regeneration of the cartilage
simulating cartilage-producing cells (chondrocytes). PMF simulation
can also restore the joints viability by increasing the activity of
the nerves innervating this particular joint.
[0080] 3. Nerve regeneration. It is known that sustained neuronal
activity is essential for nerve regeneration and for
re-establishing damaged innervation of the internal organs.
Therefore, PMF-induced increase in neuronal excitability of the
peripheral nerves, or spinal cord following injury to each or both
could increase the nerve capability to regenerate and restore lost
contact with target organs, and to improve propagation of compound
action potentials within the spinal cord.
[0081] 4. Hypo- and areflexia. These are pathologies that are
expressed as weak or absent reflexes. Very often these pathologies
are related to deficits in transmission of information in the
spinal cord, or diminished efficiency of the peripheral nerves to
transmit a compound action potential, and PMF exposure could
restore the strength of the reflex.
[0082] 5. A chronic Bell's palsy: This pathology, expressed as
facial nerve paralysis is currently incurable. Increasing the
excitability of the facial tissue by exposure to PMF could have a
great potential to cure such condition.
[0083] 6. Selective stimulation of internal organs: Magnetic
stimulation of the autonomic nerves or ganglion can specifically
enhance the function of an organ innervated by stimulated nerve or
ganglion. For example, exposure of the colon to PMF could increase
its enteric system excitability to treat a patient with irritable
bowel. Increasing the excitability of the sacral region could
improve the function of several organs of the pelvic region. In a
patient with weak cardiac output, which is usually due to low
compound action potential, exposure to PMF could offer a treatment
solution.
[0084] 7. Channelopathies. The mechanism of generation and
propagation of the action potential is linked to the function of
specific structures in the membrane of the nerve cells called ion
channels. These channels allow ions, like sodium, potassium,
calcium and chloride to diffuse in and out of the cell. Several
disorders of the nervous system are related to pathology of these
channels. These pathologies are collectively called
"channelopathies". Applicant has discovered that the action of PMF
in mostly exerted through modulation of the function of the sodium
channels.
[0085] Although some embodiments of the invention has been shown
and described, many features may be varied, as will readily be
apparent to those skilled in this art. Thus, the foregoing
description is illustrative and not limiting, the invention being
defined by the following claims.
* * * * *
References